Worm-drive power tong

ABSTRACT

A tong for applying torque to a tubular and a method of using a tong, of which the tong includes a rotary ring defining an inner profile through which the tubular is received, the inner profile defining a plurality of pockets extending radially outward and a plurality of cam surfaces circumferentially between the plurality of pockets, and a plurality of engaging members disposed within the rotary ring. The plurality of engaging members are movable from a retracted position at least partially in the plurality of pockets to an engaging position in which the plurality of engaging members are positioned along the plurality of cam surfaces. The tong also includes a plurality of cam followers extending through the rotary ring, and a worm drive including a helical ridge. The plurality of cam followers engage the helical ridge so as to transmit a substantially tangential force to the rotary ring.

BACKGROUND

Tubular handling equipment is used on an oil rig to lower casing and other tubulars into the wellbore (“trip-in”). During trip-in, an elevator picks up a length of one or more joints of tubular from a rack and brings the tubular into position above a “stump” or open connection of a previously-run tubular. The stump is typically supported at the rig floor by a spider, which transmits the weight of the deployed tubular string to the rig floor. An operator may then guide the new length of tubular (an “add-on” tubular) into position over the stump, i.e., at well center. The operator may then assist in stabbing the add-on tubular into the open connection of the stump.

Once this occurs, the operator may engage a power tong onto the add-on tubular and apply a torque to the add-on tubular. The torque causes the add-on tubular to rotate into connection with the stump. The tong is then disengaged, the elevator engages the add-on tubular, and the spider may disengage from the tubular string, leaving the weight of the tubular string held by the elevator. The elevator then lowers the tubular string into the well, until nearing the rig floor, at which point the spider is re-engaged, and the process starts again.

The aforementioned tongs are designed to impart and withstand high torsional loads. Typically, a tong includes a drive train made of a set of spur gears, which amplify a torque produced by a motor. The amplified torque is then transmitted to a rotary gear, which applies the torque to the tubular. Other tong designs employ a worm-gear drive, in which a helical tooth mates with canted teeth of a driven gear. Thus, rotation of the helical tooth results in rotation of the driven gear, which the tong converts into rotation of the tubular.

Conventional tongs, however, occupy a substantial footprint on a rig. Further, tongs are typically designed to engage a single diameter of pipe, requiring time-consuming equipment changes when the size (diameter) of the pipe being run changes. Additionally, tongs are often designed to allow lateral entry of the pipe to within the tong and exit therefrom, but may not be configured to allow a box-end of a pipe joint to pass axially therethrough.

SUMMARY

Embodiments of the disclosure may provide a tong for applying torque to a tubular. The tong includes a rotary ring defining an inner profile through which the tubular is received, the inner profile defining a plurality of pockets extending radially outward and a plurality of cam surfaces circumferentially between the plurality of pockets, and a plurality of engaging members disposed within the rotary ring. The plurality of engaging members are movable from a retracted position at least partially in the plurality of pockets to an engaging position in which the plurality of engaging members are positioned along the plurality of cam surfaces. The tong also includes a plurality of cam followers extending through the rotary ring, and a worm drive including a helical ridge. The plurality of cam followers engage the helical ridge so as to transmit a substantially tangential force to the rotary ring.

Embodiments of the disclosure may also provide a method for rotating a tubular using a tong. The method includes receiving a tubular into a receiving hole in a tong, and activating a motor. Activating the motor causes a helical ridge to rotate in a first direction, the helical ridge applying a linear force on one or more cam followers connected to a rotary ring, causing the rotary ring to rotate relative to a plurality of engaging members. Rotating the rotary ring relative to the plurality of engaging members causes the plurality of engaging members to move radially inwards into engagement with the tubular and to rotate the tubular after engaging the tubular.

Embodiments of the disclosure may further provide a tong that includes a motor, a helical ridge coupled to the motor such that the motor drives the helical ridge to rotate, a rotary ring defining a plurality of pockets and a plurality of cam surfaces in an inner profile thereof, and a plurality of cam followers connected to the rotary ring and extending axially therefrom, the plurality of cam followers being positioned to be engaged by the helical ridge. The helical ridge applies a linear force on the plurality of cam followers when the cam followers are engaged by the helical ridge, and wherein the linear force causes the rotary ring to rotate. The tong also includes a plurality of jaws movable along the inner profile of the rotary ring. The plurality of jaws are positioned at least partially within respective pockets of the plurality of pockets when the tong is in a retracted position, and the plurality of jaws engage the plurality of cam surfaces when the tong is in an engaging position.

The foregoing summary is intended merely to introduce a subset of the features more fully described of the following detailed description. Accordingly, this summary should not be considered limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawing, which is incorporated in and constitutes a part of this specification, illustrates an embodiment of the present teachings and together with the description, serves to explain the principles of the present teachings. In the figures:

FIG. 1 illustrates a perspective view of a power tong, according to an embodiment.

FIG. 2A illustrates another perspective view of the tong showing a worm-drive thereof, according to an embodiment.

FIG. 2B illustrates a simplified bottom view of the tong, showing another embodiment of the worm drive.

FIG. 3 illustrates a perspective view of the tong with a top guard thereof removed, revealing a cage plate thereof, according to an embodiment.

FIG. 4 illustrates a perspective view of the tong with the top guard and the cage plate removed, according to an embodiment.

FIG. 5 illustrates a top view of the tong with the top guard and cage plate removed, showing a first embodiment of the jaws, according to a first embodiment.

FIG. 6A illustrates a perspective view of a cage plate of the tong with jaws retracted, according to an embodiment.

FIG. 6B illustrates another perspective view of the cage plate of the tong with jaws extended radially inward, according to an embodiment.

FIG. 6C illustrates a sectional view of the tong, according to an embodiment.

FIG. 7 illustrates a top, schematic view of a second embodiment of a cam surface of the tong.

FIG. 8 illustrates a top view of the tong with the jaws in a retracted configuration, according to an embodiment.

FIG. 9 illustrates a top view of the tong with the jaws in a first engaging position, according to an embodiment.

FIG. 10 illustrates a top view of the tong in a second engaging position, according to an embodiment.

FIG. 11 illustrates a flowchart of a method for rotating a tubular using a tong, according to an embodiment.

It should be noted that some details of the figure have been simplified and are drawn to facilitate understanding of the embodiments rather than to maintain strict structural accuracy, detail, and scale.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments of the present teachings, examples of which are illustrated in the accompanying drawing. In the drawings, like reference numerals have been used throughout to designate identical elements, where convenient. In the following description, reference is made to the accompanying drawing that forms a part thereof, and in which is shown by way of illustration a specific exemplary embodiment in which the present teachings may be practiced. The following description is, therefore, merely exemplary.

In general, the present disclosure provides a tong for rotating a tubular (e.g. a casing) and/or otherwise applying a torque thereto. In some embodiments, the tong includes a worm drive that has input power supplied by a motor (e.g., a hydraulic, electric, or pneumatic motor). The worm drive may engage cam followers attached to a rotary section of the tong. The rotary section generally includes a cage plate assembly, a rotary ring, and jaws. Input rotation of the worm drive may cause the screw thereof to apply a linear force to the cam followers, which is translated to a tangential force on the rotary section, causing the rotary ring of the rotary section to rotate. Initially, the cage plate assembly and the jaws are restrained from rotating, such that rotation of the rotary ring causes jaws to move radially inwards across a range of radial positions. When a tubular is received through the tong, such rotation causes the jaws to engage the tubular. Continued rotation of the rotary ring may, after such engagement, cause cage plate and jaws to rotate along with the rotary ring, and thereby rotate the tubular. The worm drive may be reversed, which may reverse the rotation of the rotary ring and cause the jaws to retract and move radially outward (e.g., into pockets) so as to disengage from the tubular. The jaws may retract far enough away from the tubular to allow passage of the tubular, e.g., including the box end thereof, vertically through the tong. These and other features will be described in greater detail below with reference to several example embodiments.

Turning now to the illustrated embodiments, FIG. 1 illustrates a raised, perspective view of a tong 100, according to an embodiment. The tong 100 may be a power tong, which may be configured to rotate a tubular received therethrough. The tong 100 may include a rotatable section 102 and a stationary section 104. The rotatable section 102 may be coupled to the stationary section 104 and may be driven to rotate with respect thereto. Further, the rotatable section 102 may be annular and may include a receiving hole 106 therethrough. As will be described in greater detail below, the tong 100 may include jaws or any other type of engaging structures that extend radially into the receiving hole 106 to grip a tubular received therethrough.

In an embodiment, the rotatable section 102 may include a top guard 108, which may be generally disk-shaped and may serve to protect other tong 100 components from damage, e.g., if an elevator or another object lands on the tong 100. The rotatable section 102 may also include a removable cover 110, which may be generally L-shaped in cross section (e.g., extending vertically and then horizontally to meet the top guard 108) and configured to cover an access gap, as will be described in greater detail below. The cover 110 may, for example, be fastened to the top guard 108 via bolts.

Further, the rotatable section 102 may include a guide 112, which may be coupled with or disposed within the top guard 108. The guide 112 may be annular and beveled or tapered, so as to receive and direct an end of a tubular therethrough. The guide 112 may be positioned in alignment with the receiving hole 106, and thus may serve to guide the tubular into the receiving hole 106. Further, the guide 112 may be provided in at least two pieces (e.g., segments 112A, 112B), which may be separately removable, e.g., to allow for lateral removal of a tubular from within the receiving hole 106.

The rotatable section 102 may also include a cage plate 114 and a rotary ring 118. For example, the cage plate 114 may be disposed vertically below and adjacent to the top guard 108. The rotary ring 118 may be below the cage plate 114 and may be seated on the stationary section 104, and configured to rotate with respect thereto. Further, the rotary ring 118 may initially be rotatable relative to the cage plate 114.

The top guard 108 may include openings 119 extending therethrough, and through which backing pins 117A, 117B are received. As will be described in greater detail below, the backing pins 117A, 117B may be held generally stationary with respect to the cage plate 114 and the top guard 108 and may serve to provide an end range for relative movement between the rotary ring 118 and the cage plate 114.

The stationary section 104 may include a brake band 116 and a body 120 to which the rotatable section 102, e.g., the rotary ring 118, may be movably coupled. The brake band 116 may extend at least partially around a circumference of the cage plate 114. The body 120 may support the tong 100 and may be coupled to an external structure, whether stationary (e.g., the rig floor) or mobile (e.g., a lifting assembly, carriage, hoist, etc.). Further, the body 120 may be coupled to a motor 122 via motor mounts 124. The body 120 may also include an access door 126, which may be opened, e.g., to allow lateral movement of a tubular therethrough.

The motor 122 may be energized to rotate the rotatable section 102 relative to the stationary section 104. Such rotation may result in a reactionary torque load being applied from the rotatable section 102 to the body 120. The stationary section 104 may thus include a load cell 128 positioned between the motor mount 124 and the body 120, which may measure such torque. The measured torque may provide information about the torque load applied by the tong 100 onto a tubular connection, thereby indicating when the connection is fully made. In an embodiment, the motor 122 may be a hydraulic motor, but in other embodiments, other types of drive systems may be employed, including electric motors and/or pneumatic motors.

FIG. 2A illustrates another perspective view of the tong 100, according to an embodiment. In this view, the body 120 (FIG. 1) is omitted for purposes of illustration. The tong 100 includes a shield plate 200, which is partially shown as transparent to allow illustration of the internal components of the drive system for the tong 100. As shown, the motor 122 may be configured to drive a shaft 202 that includes a helical ridge or “tooth” 204, e.g., forming a worm drive.

The rotatable section 102 may include cam followers 206, which may extend downward therefrom, as shown, for example. The cam followers 206 may, in some embodiments, be cylindrical and may or may not include bearing elements between the outer roller and inner shaft of the cam follower. The cam followers 206 may be disposed in a circular pattern near or along the radially outer periphery of the rotatable section 102. In particular, the cam followers 206 may extend downward from the rotary ring 118, and may be coupled thereto such that forces incident on the cam followers 206 are transmitted to the rotary ring 118.

The helical ridge 204 may engage the cam followers 206. Accordingly, the helical ridge 204 may be positioned at least partially axially below the rotary ring 118, such that the helical ridge 204 and the shaft 202 radially overlap the stationary section 104 and the rotatable section 102 (e.g., as seen in a top view of the tong 100), which may provide for a compact footprint of the tong 100. Further, the shaft 202 and the helical ridge 204 may be oriented in a generally tangential direction to the rotary ring 118. As the helical ridge 204 turns, it may engage and apply a linear force on the cam followers 206. The cam followers 206 may transmit this force to the rotary ring 118 as a tangential force applied thereto. This in turn results in a torque force on the rotary ring 118, causing the rotary ring 118 to rotate about the receiving hole 106.

In some embodiments, the cam followers 206 and the helical ridge 204 may be sized and configured such that at least one, at least two, or more cam followers 206 engage the helical ridge 204 at any given point during rotation, e.g., when one cam follower 206 rotates out of the helical ridge 204, another enters into it. This may maintain a smooth rotation of the rotary ring 118 when the helical ridge 204 is turned by the motor 122. The tong 100 may also include a speed reducer and encoder 208, which may measure a speed and/or an angular position of the shaft 202.

FIG. 2B illustrates a simplified, bottom view of the tong 100, illustrating another embodiment. As shown, the cam followers 206 extend from the rotary ring 118, e.g., to a location axially below the rotary ring 118. The motor 122 is also present, and is operable to drive a pair of helical ridges 250, 252 via two shafts 254, 256, respectively. The shafts 254, 256 may be connected together via a gear box 258, which may allow the shafts 254, 256 to be rotated by a single motor 122, while being disposed at an angle relative to one another (e.g., about 90 degrees, as shown). Accordingly, the shafts 254, 256 and the helical ridges 250, 252 may both extend tangentially to the rotary ring 118, such that the helical ridges 250, 252 engage the cam followers 206, thereby applying a tangentially-directed force on the rotary ring 118, causing the rotary ring 118 to rotate.

It will be appreciated that three or more helical ridges 250, 252 may be employed, with the embodiments above describing one helical ridge and two helical ridges being merely examples. Further, a variety of arrangements for driving the shafts 254, 256 in multi-shaft embodiments are contemplated (e.g., both shafts 254, 256 and the motor 122 could be connected to the gear box 258 such that the gear box 258 is between the motor 122 and the shafts 254, 256) and may be used within the scope of the present disclosure.

FIG. 3 illustrates a raised perspective view of the tong 100 with the top guard 108 and cover 110 removed for purposes of illustration, according to an embodiment. The cover 110 (e.g., FIG. 1) covers an access gap 300, which may be formed in the cage plate 114. A removable portion 304 of the rotary ring 118 may extend through the access gap 300. The removable portion 304 of the rotary ring 118 may be hinged or detachable, e.g., along with the cover 110 (FIG. 1) and at least one segment 112B of the guide 112 (FIG. 1), so as to allow lateral entry or exit of a tubular into the receiving hole 106.

In addition, FIG. 3 illustrates the tops of the cam followers 206 extending through the rotary ring 118. The cam followers 206 may be received through bores formed in the rotary ring 118. Further, the tops of the cam followers 206 may extend into a passage 302 formed in the cage plate 114, thereby allowing the cam followers 206 to move, along with the rotary ring 118, circumferentially with respect to the cage plate 114. The cam followers 206 may also extend downward, through the rotary ring 118 and below the body 120, so as to engage the helical ridge 204, as shown in and described above with reference to FIG. 2A. The cam followers 206 may include first rollers 610 below the rotary ring 118, which may be configured to engage the helical ridge 204 (FIG. 2) below the rotary ring 118. The cam followers 206 may also include second rollers 612 above and seated on the rotary ring 118, such that the cam followers 206 are free to rotate within the bore with respect to the rotary ring 118. The cam followers 206 may also each include a first shaft 614A and a second shaft 614B. The first roller 610 may be positioned around the first shaft 614A, and the second roller 612 may be positioned around the second shaft 614B. The first and second shafts 614A, 614B may be connected together. In some embodiments, a single shaft or three or more shafts may be employed.

FIG. 4 illustrates a raised perspective view of the tong 100 with the top guard 108 and the cage plate 114 removed for purposes of illustration, according to an embodiment. FIG. 5 illustrates a top view of the tong 100, also with the top guard 108 and the cage plate 114 removed for purposes of illustration, according to an embodiment. Referring to both FIGS. 4 and 5, the tong 100 may include a plurality of engaging members or “jaws” (three shown: 400A, 400B, 400C), which may be movable radially (i.e., toward and away from a center of the receiving hole 106) to grip a tubular. The jaws 400A-C may include teeth, wickers, buttons, grit, high-friction surfaces, or any other structure configured to grip a tubular and transmit a high radial and torque load to the tubular. For example, the jaws 400A-C may include replaceable inserts or “dies” providing such marking structures, which may be readily replaceable. The jaws 400A-C may be coupled with the cage plate 114, as will be described in greater detail below, and may be configured to slide radially, between a retracted position and an engaging position, with respect thereto.

The brake band 116 may be tight around the cage plate 114, thereby generating friction that prevents the cage plate 114 from rotating relative to the brake band 116, at least initially. In turn, the brake band 116 may be coupled with the body 120 via one or more posts 401 (two are shown), which may prevent the brake band 116 from rotating relative to the body 120. The brake band 116 may be pulled tight between the posts 401 so as to provide the friction on the cage plate 114. In other embodiments, other types of braking structures that initially allow the rotary ring 118 to rotate relative to the cage plate 114 may be employed.

The jaws 400A-C are illustrated in the retracted position. In particular, in this embodiment, the rotary ring 118 includes an inner profile 402 in which one or more pockets (three are shown: 404A, 404B, 404C) are defined, for example, one for each of the jaws 400A-C, although additional pockets could also be provided. The pockets 404A-C may extend radially outward from the inner profile 402, providing a space into which the jaws 400A-C may be retracted and held away from the tubular received through the receiving hole 106. Thus, the pockets 404A-C may allow the jaws 400A-C to retract, which may allow the tong 100 to slide over tubular connections, upsets, couplings, etc. The inner profile 402 may also include one or more cam surfaces (three shown: 406A, 406B, 406C), which may be arcuate segments that have a radius of curvature that is less than the overall inner profile 402, or may otherwise tend to extend radially inwards as proceeding in a circumferential direction around the inner profile 402 of the rotary ring 118. Each of the cam surfaces 406A-C may define an apex 409, where the inner profile 402 may transition from extending radially inward to extending radially outward. The cam surfaces 406A-C provide an extended range of radial dimensions for tubulars that may be gripped using the jaws 406A-C.

The rotary ring 118 may define backing slots 408A, 408B that receive the respective backing pins 117A, 117B therein. As noted above, the backing pins 117A, 117B may be stationary with respect to the cage plate 114, and thus, initially, the rotary ring 118 may rotate relative to the backing pins 117A, 117B. Accordingly, the backing pins 117A, 117B may move within the slots 408A, 408B as the rotary ring 118 rotates relative to the cage plate 114, until the backing pins 117A, 117B engage an end of the respective slots 408A, 408B or the rotary ring 118 is otherwise prevented from continued rotation relative to the cage plate 114 (e.g., by the jaws 400A-C engaging a tubular). Thus, the slots 408A, 408B may be arcuate to accommodate such circumferential movement, and may extend roughly along the maximum range of relative rotation to be allowed between the rotary ring 118 and the jaws 400A-C. It will be appreciated that the illustrated embodiment including two backing slots 408A, 408B and two backing pins 117A, 117B, is merely one example, and any number of slots and/or backing pins may be employed.

Further, the tong 100 may include one or more return springs 410, e.g., two for each of the jaws 400A-C, as shown. Each of the return springs 410 may extend between posts 412, 414, with the post 414 being stationary with respect to and attached to the cage plate 114 (not visible), and the posts 412 being radially movable along with the jaws 400A-C, as will be described in greater detail below. Accordingly, the spring 410 may bias the jaws 400A-C radially outwards, so as to pull the jaws 400A-C back into the pockets 400A-C when they are circumferentially aligned therewith. The return springs 410 may be connected to pins 412, 414. In turn, the pins 412 may be connected to the jaws 400A-C and the pins 414 may be connected to the cage plate 414.

FIG. 6A illustrates a top, perspective view of the cage plate 114 of the tong 100, according to an embodiment. As shown, the cage plate 114 may include a plurality of pinholes (four are shown: 601A, 601B, 601C, 601D). The pinholes 601A, 601B may be aligned with the first backing slot 408A of the rotary ring 118 (see, e.g., FIGS. 4 and 5), and the pinholes 601C, 601D may be aligned with the second backing slot 408B of the rotary ring 118. Accordingly, the backing pin 117A may extend through either of the pinholes 601A, 601B and be received into the first backing slot 408A, and/or the backing pin 117B may extend through either of the pinholes 601C, 601D and into the second backing slot 408B. The pinholes 601A-D may also be aligned with respective openings 119 in the top guard 108 (FIG. 1).

The pinholes 601B, 601D may correspond to a make-up or “make” position (as indicated), which, when a backing pin 117A, 117B is received therethrough and into the corresponding slot 408A, 408B, may allow for a range of rotation of the rotary ring 118 in a first circumferential direction, while initially preventing rotation in a second, opposite circumferential direction. The pinholes 601A, 601C may correspond to a break out or “break” position, which, when a backing pin 117A, 117B is received therethrough, may allow rotation of the rotary ring 118 relative to the cage plate 114 in the second circumferential direction, while initially preventing rotation in the first direction. As noted above, the backing pins 117A, 117B may be removable through the top guard 108 via the openings 119, and thus the direction of rotation allowed by the backing pins 117A, 117B may be readily reversed by removing the backing pins 117A, 117B and putting them in the pinhole that allows the desired rotation. In some embodiments, two backing pins 117A, 117B may be provided, each going through one of the make pinholes 601B, 601D (as shown), or through one of the break pinholes 601A, 601C. In other embodiments, any other number of backing pins, pinholes, and/or backing slots may be employed.

Further, radially-extending spring slots 603 may be provided, which may receive the posts 412 by which the springs 410 are attached to the jaws 400A-C. The posts 414 may be fixed in position relative to the cage plate 114, as noted above, while the posts 412 may be movable radially in the spring slots 603 as the jaws 400A-C move radially.

FIG. 6B illustrates another perspective view of the cage plate 114 of the tong 100, according to an embodiment. As can be seen by comparison with the view of FIG. 6A, the jaws 400A-C have moved radially inward. As such, the posts 412 have moved correspondingly in the slots 603, and the spring 410 has been extended. As will be described in greater detail below, this radially-inward movement of the jaws 400A-C may be caused by relative rotation between the rotary ring 110 and the cage plate 114. Further, the jaws 400A-C may be permitted to move radially with respect to the cage plate 114, but may be prevented from circumferential movement (i.e., rotation about the centerline of the tong 100) prevented from rotating relative to the cage plate 114.

With continuing reference to FIGS. 6A and 6B, FIG. 6C illustrates a vertical cross-sectional view of the tong 100, according to an embodiment. The view provides an illustration of the linkage between the cam followers 206 and the rotary ring 118, among other things. As shown, the cam followers 206 may extend axially through the body 120, where they may rotate into and out of engagement with the helical ridge 204 of the worm drive.

The cam followers 206 may also extend at least partially (e.g., entirely) through the rotary ring 118, and upwards into the passage 302 in the cage plate 114. Accordingly, force in the horizontal plane on the cam followers 206 may be transmitted to the rotary ring 118 through the cam followers 206. In particular, the helical ridge 204 may impart a linear force on the cam followers 206, which in turn generates a tangential force on the rotary ring 118, thereby causing the rotary ring 118 to rotate.

As mentioned above, and also viewable in FIG. 6A, the jaws 400A-C (jaws 400A and 400C are visible in FIG. 6B) may be coupled with the cage plate 114 such that they are movable radially, along a generally linear path, with respect thereto, but may be prevented from rotating (travelling in a circumferential direction) with respect to the cage plate 114. For example, the cage plate 114 may include T-slots 600, which may be radially oriented. Each one of the jaws 400A-C may fit in a separate T-slot 600, thereby allowing such radial motion but preventing movement in the circumferential direction relative to the cage plate 114.

In the embodiment illustrated in FIGS. 4 and 5, the jaws 400A-C slide along the rotary ring 118 as the rotary ring 118 rotates. In the embodiment of FIG. 6, the jaws 400A-C are additionally provided with rollers 602, which may roll along the rotary ring 118, e.g., the pockets 404A-C (see FIG. 4) and cam surfaces 406A-C (see FIG. 4), so as to reduce friction in such movement. The inclusion of such rollers may be optional in any of the embodiments discussed herein.

FIG. 7 illustrates a partial, schematic view of another embodiment of the rotary ring 118, according to an embodiment. The pocket 404A and cam surface 406A are illustrated, but may be representative of the remaining pockets and cam surfaces, as shown, e.g., in FIG. 5. As illustrated in FIG. 7, the cam surface 406A may have a stepped profile, including a first surface 700 and a second surface 702. The first surface 700 may extend at a generally uniform radius across an arc of a certain angle, until reaching a transition surface or “ramp” 704. The transition surface 704 may extend generally linearly, or at a different radius of curvature than the first surface 700, and may extend to the second surface 702. The second surface 702 may thus begin at a position that is radially offset from where the first surface 700 met with the transition surface 704. The second surface 702 may then extend from the transition surface 704 at the same or a different radius of curvature than the first surface 700.

Accordingly, in operation, one of the jaws (e.g., the jaw 400A) may initially sit in the pocket 404A, but may be pushed out of the pocket 404A by the clockwise rotation of the rotary ring 118, as the jaw 400A is held stationary by the cage plate 114. The jaw 400A may thus ride up onto the first surface 700 of the cam surface 406C, until reaching the transition surface 704. The transition surface 704 may abruptly push the jaw 400A radially inward, and then onto the second surface 702. The jaw 400A may then continue to move radially inward as the rotary ring 118 continues to rotate. This stepped profile for the cam surface 406A may be capable of further extending the range of diameters of tubulars that may be effectively gripped by the tong 100.

Referring now to FIGS. 8-10, an example of operation of the tong 100 is shown. In such operation, the rotary ring 118 may be driven to rotate relative to the body 120 by the motor 122 and the linkage provided by the cam followers 206. The jaws 400A-C may be coupled with the cage plate 114 such that they are non-rotational with respect thereto, but radially slidable relative to the cage plate 114. The cage plate 114 may be initially secured against rotation by friction force applied by the brake band 116. Thus, as the rotary ring 118 begins to rotate relative to the body 120, the rotary ring 118 may also rotate relative to the cage plate 114 and the jaws 400A-C. By such rotation, the jaws 400A-C may be forced out of the pockets 404A-C and circumferentially, as well as radially inward, onto the cam surfaces 406A-C. Continued rotation of the rotary ring 118 relative to the jaws 400A-C may cause the jaws 400A-C to move farther radially inward until reaching an engaging position, where the jaws 400A-C are designed to engage a tubular received in the receiving hole 106. In embodiments in which the backing pins 117A, 117B and slots 408A, 408B are provided, if the jaws 400A-C do not engage a tubular after a maximum amount of rotation, the backing pins 117A, 117B may engage an end of the respective slots 408A, 408B to prevent continued relative rotation by overcoming the holding force applied by the brake band 116 (see, e.g., FIG. 1) on the cage plate 114. When this occurs, the cage plate 114 may rotate with the rotary ring 118. The maximum range of rotational movement allowed by the backing pins 117A, 117B in the backing slots 408A, 408B may correspond to where the jaws 400A-C reach the apex 409 of each of the cam surfaces 406A-C (see FIG. 4).

When the jaws 400A-C engage a tubular, such as tubular 900, shown in FIG. 9, a force between the jaws 400A-C and the cam surfaces 406A-C may increase, as the cam surfaces 406A-C wedge the jaws 400A-C tighter against the tubular 900. This may overcome the holding force applied on the cage plate 114 by the brake band 116. Thus, as the rotary ring 118 continues to rotate, the jaws 400A-C and the cage plate 114 may also rotate. Further, this may also cause the tubular 900 engaged by the jaws 400A-C to rotate with respect to the body 120.

The tong 100 may also be configured to engage a second tubular 1000, as shown in FIG. 10. The second tubular 1000 may have a smaller diameter than the first tubular 900, and thus further extension of the jaws 400A-C may be called for to accomplish such engagement. Thus, the rotary ring 118 rotation is allowed to rotate farther in the first direction, such that the jaws 400A-C continue to ride along the cam surfaces 406A-C until extending far enough inwards to engage the tubular 1000. As such, tubulars of different diameters may be engaged by the tong 100, without reconfiguration of the tong 100 itself; the rotary ring 118 simply rotates until the jaws 400A-C engage the tubular, regardless of the tubular size, within a design range.

In either example case (FIG. 9 or 10), when release of the tubular 900 or 1000 is desired, the rotation of the rotary ring 118 may reverse. Upon reverse rotation of the rotary ring 118, the return springs 410 may hold the jaws 400A-C radially outwards against the cam surfaces 406A-C and eventually force the jaws 400A-C back into the pockets 404A-C. The pockets 404A-C may thus allow the jaws 400A-C to retract, which may allow the tong 100 to remain received around a tubular while sliding over a collar, centralizer, tool, or connection between two pipes, as will be described in greater detail below.

Embodiments of the disclosure may also include a method for operating such tongs. FIG. 11 illustrates a method 1100 for rotating a tubular using a tong, according to an embodiment. The method 1100 is described herein with reference to the tong 100, according to the various embodiments of FIGS. 1-10, but it will be appreciated that other embodiments of the method 1100 may employ other types of tongs, and thus the method should not be considered limited to any particular structure unless otherwise stated.

The method 1100 may include positioning a tubular within the receiving hole 106 of the tong 100, as at 1102. This may be accomplished, e.g., by vertically translating the tubular through the top of the receiving hole 106, moving the tong 100 upwards (as with a lifting assembly), or by receiving the tubular laterally through the access door 126, with the cover 110 and at least a segment 112B of the guide 112 removed, as well as the access door 126 (with the portion 304 of the cage plate 114 and/or rotary ring 118) removed or swung open.

The method 1100 may then proceed to engaging the tubular using jaws 400A-C of the tong 100 by activating the motor 122 of the worm drive, which causes the helical ridge 204 to rotate in a first direction, as at 1104. Rotation of the helical ridge 204 applies a tangential force on the rotary ring 118 via engagement with the cam followers 206, resulting in the rotary ring 118 rotating in a first circumferential direction. The rotation of the rotary ring 118 in the first circumferential direction causes the jaws 400A-C to move out of the pockets 404A-C and onto the cam surfaces 406A-C as described above. Eventually, the rotation of the rotary ring 118 relative to the cage plate 114 is stopped, either by the jaws 400A-C engaging the tubular or the backing pin(s) 117A and/or 117B engaging an end of the respective slots 408A, 408B, thereby overcoming the resistance to rotation that the brake band 116 applies on the cage plate 114. With the jaws 400A-C engaged with the tubular, and the motor 122 remaining active, the tong 100 may apply a torque to the tubular, causing the tubular to rotate, as at 1106. In turn, threads of the tubular may be advanced into engagement with mating threads of another tubular (e.g., a box-end of a stump).

The method 1100 may then include disengaging the jaws 400A-C of the tong 100 from the tubular, as at 1108, by stopping and reversing the direction of the rotation of the helical ridge 204, e.g., by activating the motor 122 to rotate in a second, reverse direction. The jaws 400A-C may slide back along the cam surfaces 406A-C, and, as they are biased radially outward by the springs 410, may eventually slide back into the respective pockets 404A-C.

With the jaws 400A-C retracted, the tubular may move, relative to the tong 100, such that, for example, an expanded, box-end of the tubular may move through the tong 100, as at 1110. This may occur before or after rotating the tubular using the tong 100. In some embodiments, the tubular may be laterally removed from the tong 100, as described above. The method 1100 may also include engaging and rotating a second tubular of a second diameter that is different from the diameter of the first tubular, again using the tong, and without reconfiguring the tong 100, as at 1112.

While the present teachings have been illustrated with respect to one or more implementations, alterations and/or modifications may be made to the illustrated examples without departing from the spirit and scope of the appended claims. In addition, while a particular feature of the present teachings may have been disclosed with respect to only one of several implementations, such feature may be combined with one or more other features of the other implementations as may be desired and advantageous for any given or particular function. Furthermore, to the extent that the terms “including,” “includes,” “having,” “has,” “with,” or variants thereof are used in either the detailed description and the claims, such terms are intended to be inclusive in a manner similar to the term “comprising.” Further, in the discussion and claims herein, the term “about” indicates that the value listed may be somewhat altered, as long as the alteration does not result in nonconformance of the process or structure to the illustrated embodiment. Finally, “exemplary” indicates the description is used as an example, rather than implying that it is an ideal.

Other embodiments of the present teachings will be apparent to those skilled in the art from consideration of the specification and practice of the present teachings disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the present teachings being indicated by the following claims. 

What is claimed is:
 1. A tong for applying torque to a tubular, comprising: a rotary ring defining an inner profile through which the tubular is received, the inner profile defining a plurality of pockets extending radially outward and a plurality of cam surfaces circumferentially between the plurality of pockets; a plurality of engaging members disposed within the rotary ring, wherein the plurality of engaging members are movable from a retracted position at least partially in the plurality of pockets to an engaging position in which the plurality of engaging members are positioned along the plurality of cam surfaces; a plurality of cam followers extending through the rotary ring; and a worm drive comprising a helical ridge, wherein the plurality of cam followers engage the helical ridge so as to transmit a substantially tangential force to the rotary ring, to rotate the rotary ring.
 2. The tong of claim 1, wherein the plurality of cam surfaces each comprise an arcuate shape.
 3. The tong of claim 1, wherein the plurality of engaging members each comprise a roller that rolls along one of the plurality of cam surfaces when the rotary ring is rotated relative to the engaging members.
 4. The tong of claim 1, wherein the plurality of cam surfaces each define a stepped profile comprising a first arcuate surface, a second arcuate surface, and a transition ramp positioned therebetween.
 5. The tong of claim 1, wherein the plurality of engaging members are configured to rotate with the rotary ring after moving along at least a portion of the plurality of camming surfaces.
 6. The tong of claim 1, further comprising a cage plate coupled to the rotary ring, wherein the plurality of engaging members are coupled to the cage plate such that the plurality of engaging members are slidable with respect to the cage plate in a radial direction, but are prevented from moving circumferentially relative to the cage plate.
 7. The tong of claim 6, wherein the cage plate comprises a plurality of radial slots, the radial slots slidably receiving the engaging members.
 8. The tong of claim 6, further comprising: a stationary body, the rotary ring being rotatable relative to the stationary body; and a brake band coupled to the stationary body and received at least partially around the cage plate, to apply a friction force on the cage plate that resists rotation of the cage plate relative to the stationary body.
 9. The tong of claim 8, wherein a portion of the rotary ring and a portion of the stationary body are movable to allow lateral removal of the tubular from within the rotary ring.
 10. The tong of claim 8, wherein the rotary ring defines one or more arcuate backing slots, the tong further comprising: a top guard comprising openings, wherein the cage plate comprises a make pinhole and a break pinhole, the make pinhole being aligned with one of the openings and the break pinhole being aligned with another one of the openings; and a backing pin received through one of the openings and through the make pinhole or the break pinhole, and into the backing slot, wherein the backing pin in the backing slot limits a range of relative rotation between the cage plate and the rotary ring.
 11. The tong of claim 1, wherein the plurality of cam followers each comprise a first roller configured to engage the helical ridge, a second roller seated on the rotary ring, and a shaft extending therebetween.
 12. The tong of claim 1, wherein the plurality of cam followers extend axially into the rotary ring and the helical ridge and the rotary ring are radially overlapping.
 13. A method for rotating a tubular using a tong, comprising: receiving a tubular into a receiving hole in a tong; and activating a motor, wherein activating the motor causes a helical ridge to rotate in a first direction, the helical ridge applying a linear force on one or more cam followers connected to a rotary ring, causing the rotary ring to rotate relative to a plurality of engaging members, wherein rotating the rotary ring relative to the plurality of engaging members causes the plurality of engaging members to move radially inwards into engagement with the tubular and to rotate the tubular after engaging the tubular.
 14. The method of claim 13, further comprising reversing a direction of the motor, wherein reversing the direction of the motor causes the helical ridge to rotate in a second direction, opposite to the first direction, which causes the rotary ring to rotate in a reverse direction, wherein the rotary ring rotating in the reverse direction allows the plurality of engaging members to retract radially outwards.
 15. The method of claim 14, further comprising laterally removing the tubular from within the rotary ring, after reversing the direction of the motor.
 16. The method of claim 14, further comprising axially removing the tubular from within the rotary ring, after reversing direction of the motor.
 17. The method of claim 14, further comprising, after activating the motor and before reversing the direction of the motor: de-activating the motor; removing a backing pin from a slot formed in the rotary ring and from a make opening defined in a cage plate that is aligned with the slot, wherein the cage plate is connected to the plurality of engaging members such that the engaging members are slidable radially with respect thereto, but prevented from moving circumferentially with respect thereto; and inserting the backing pin through a break opening aligned with the slot and into the slot, wherein the backing pin limits a relative rotation between the rotary ring and the cage plate by engaging the slot.
 18. The method of claim 17, wherein the cage plate is initially prevented from rotating with the rotary ring by a brake band connected to a stationary body of the tong, and wherein the cage plate is rotatable relative to the stationary body when a friction force applied by the brake band on the cage plate is overcome.
 19. The method of claim 14, wherein the plurality of engaging members retract radially outward into respective pockets formed in the rotary ring.
 20. A tong, comprising: a motor; a helical ridge coupled to the motor such that the motor drives the helical ridge to rotate; a rotary ring defining a plurality of pockets and a plurality of cam surfaces in an inner profile thereof; a plurality of cam followers connected to the rotary ring and extending axially therefrom, the plurality of cam followers being positioned to be engaged by the helical ridge, wherein the helical ridge applies a linear force on the plurality of cam followers when the cam followers are engaged by the helical ridge, and wherein the linear force causes the rotary ring to rotate; and a plurality of jaws movable along the inner profile of the rotary ring, wherein the plurality of jaws are positioned at least partially within respective pockets of the plurality of pockets when the tong is in a retracted position, and wherein the plurality of jaws engage the plurality of cam surfaces when the tong is in an engaging position.
 21. The tong of claim 20, wherein the rotary ring comprises a removable section to allow lateral removal of a tubular from within the inner profile of the rotary ring. 